It’s common For a producer who’s just starting to adopt artificial insemination to combine it with a natural boar mating. The natural service typically occurs prior to one or two A.I. services of a sow.

This method will help ensure your farrowing rate won’t decline while you’re getting used to the nuances of A.I. It also provides the benefit of heat detection with a boar.

The problem is this: Which breeding method is responsible for the majority of pigs within the sow’s litter? A primary benefit of A.I. is the efficient use of superior genetics. You can invest in a genetically high-quality boar because you need fewer boars to breed the same number of sows and gilts.

However, a natural/A.I. service breeding program will dilute some of the genetic benefit because some of the pigs will come from the boar used in the natural service.

DeKalb Swine Breeders conducted a study to identify what percentage of pigs in a litter from natural/A.I. service breedings were sired by the natural boar. Researchers used sows that were pure for the color gene. The boars in the natural service rotation were also pure for the color gene, which meant those piglets would be colored. The semen used in the A.I. matings came from pure-white line boars. Those piglets would be white.

Once a sow was identified in estrus, researchers used a boar to breed her via natural service in the morning of day one. They followed with an A.I. mating that same afternoon. The sow received a second A.I. service the next morning.

Of the 565 pigs that farrowed, 65 percent were colored, which means only 35 percent of the pigs came from the A.I. sires. Of the 52 litters that farrowed, 56 percent had all colored pigs. Mixed litters made up 19 percent of those farrowed, meaning some of the pigs were sired by the natural service and some by the A.I. boar. Only 25 percent of the litters came just from A.I. matings.

This information provides insight into the effects that a natural service boar can have on an A.I. program. Of course, the impact on individual farms will depend on the genetics and the heat-cycle patterns of a herd.

Producers who want to maximize the genetic gain from their A.I. program may want to also take measures to shorten their A.I. technician’s learning curve when introducing A.I. into their breeding program.